Notes on the lichen genus Erioderma in La Réunion

The number of species of Erioderma known in the Reunion from where the genus was described is doubled, to six. The following new records are added: Erioderma borbonicum sp. nov., E. papyraceum and E. sorediatum. These appear to be part of an ancient stock of Gondwana species which is surprising since the island is a fairly young, though it may have functioned as a refuge for species present in nearby older landmasses.